1. Field of the Invention
The present invention relates town illuminating device, an image display device equipped with the illuminating device, and a lamp unit attached to the illuminating device, and in particular is suitable for the case where the lamp unit is replaceable.
2. Disclosure of the Related Art
Currently, there are commercialized and widespread projection display devices that project a magnified image onto a screen (hereinafter referred to as “projectors”). In such projectors, a lamp is generally used as a light source and light from the lamp is modulated by an imager and is projected onto a screen.
In this arrangement, when the lamp has run out in the middle of projecting operation, image display is interrupted. To handle such a situation, the lamp is generally made replaceable in the projector.
If lamp replacement can be performed easily, it can be conceived that lamps are replaced as appropriate depending on the scenes of using the projector. For example, when making a presentation with the projector, an old lamp is used for practice and a new high-intensity lamp is used for the real presentation.
For frequent lamp replacement, each lamp needs to be managed for lifetime, compatibility with projectors, and others. As a method for the management, the lamp may be provided with a circuit board storing predetermined information. This method requires a communication path to be established between a circuit board on the projector side and the circuit board on the lamp side when the lamp is attached. Such communication path can be established by connecting two connectors on the circuit boards.
To improve workability at lamp replacement, it is desired that the connectors on the two circuit boards are connected to each other when the lamp is attached. For example, the two connectors may be arranged so as to become opposed to each other when a lamp unit is attached. This allows the two connectors to be connected simultaneously with incorporating the lamp unit into a desired position of the projector main unit.
However, a circuit board of the lamp unit is positioned distant from the lamp so as to be kept away from a heat source as much as possible. In general, the lamp is placed in the projector precisely at a desired position so that a light axis thereof can be properly positioned with respect to an optical engine. However, if the circuit board is positioned distant from the lamp as stated above, the circuit board of the lamp unit may be out of position even if the lamp is precisely positioned, whereby the connectors on the two circuit boards cannot be properly connected.